The action of pituitary and other proteinases on the glycoprotein hormones and their subunits is under study. Sub-units of several hormones are being prepared for use as substrates for thrombin and other serine proteinases. Experiments will be carried out to see if TSH alpha for example, can be split between residues 46-47 to produce large sub-unit fragments. Similar experiments will be carried out to find other specific locations for preparation of derivatives.